Abstract:
Coral calcication is essential to provide the structural foundation for coral reefs and is integral in supporting marine biodiversity reliant on reef ecosystems. The drivers for calcication in corals are undoubtedly highly complex and require several perspectives to identify vulnerabilities in the context of environmental change. Specically, ocean acidication (OA) resulting from the rise of anthropogenic carbon dioxide (CO2) emissions poses a potential threat to the physiological mechanisms that drive calcication in corals. Therefore, this report goes beyond environmental seawater chemistry to examine the physiological mechanism of calcium ion homeostasis. Calcium’s role in calcication physiology is well established, but how calcium homeostasis could shift under acidication has little been considered a signicant driver in reduced calcication. Calcium is potentially the most actively transported substrate in coral calcication, though in high chemical abundance in seawater, corals are likely utilizing the most energy to concentrate calcium at the site of calcication. We argue for increased consideration of the calcium ion in the context of OA when identifying sensitivities. The concepts proposed here are justied through a combination of results from novel RAMAN spectroscopy and molecular work that provides insight into shifts in calcium homeostasis when exposed to acidication. We speculate that future work incorporating methodologies considering calcium dynamics in OA could benet by narrowing in on what physiological mechanisms are potentially vulnerable. It is imperative that we identify what drives lower calcication in corals under OA to inform efcient directives in identifying species sensitivities to future climate change.
